后缀数组求字符串最长重复子串

#include<iostream>
#include<fstream>
#include<string>
#include<vector>
#include<deque>
#include<queue>
#include<stack>
#include<map>
#include<set>
#include<unordered_map>
#include<unordered_set>
#include<algorithm>
using namespace std;

int comlen(string s1,string s2)
{
//计算两个字符串的最长公共前缀
int i=0,j=0;
int len=0;
while(i<s1.size()&&j<s2.size())
{
if(s1[i]==s2[i])
{
i++;j++;
len++;
}
else return len;
}
return len;
}

string FindRepeatSubstr(string s)
{
vector<string> suffix; //后缀数组
string ans;
int len=0;
int maxlen=0;
int i;
for(i=0;i<s.size();i++)
{
suffix.push_back(s.substr(i,s.size()-i));
}
sort(suffix.begin(),suffix.end()); //给后缀数组排序
for(i=0;i<suffix.size()-1;i++) //计算相邻两个后缀数组的最长公共前缀
{
len=comlen(suffix[i],suffix[i+1]);
if(len>maxlen)
{
maxlen=len;
ans=suffix[i].substr(0,maxlen);
}
}
return ans;
}

int main()
{
string str;
while(cin>>str)
{
if(str=="") cout<<""<<endl;
cout<<FindRepeatSubstr(str)<<endl;
}
return 0;
}